﻿using System;
using System.Collections.Generic;
using System.Drawing.Drawing2D;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace myproject.method
{
    internal class Classvd
    {
        #region Private Fields
        private const double PI = 3.1415926535897932384626433832795;
        private const double PI2 = 6.283185307179586476925286766559;
        //private readonly int _wordsLen = 4; 
        private int _len;
        private CodeType _codetype;
        private readonly Single _jianju = (float)30.0;
        private readonly Single _height = (float)44.0;
        private string _checkCode;
        #endregion
        #region Public Property
        public string CheckCode
        {
            get
            {
                return _checkCode;
            }
        }
        #endregion
        #region Constructors
        public Classvd ( int len, CodeType ctype )   //构造函数，生成验证码
        {

            this._len = len;

            this._codetype = ctype;

        }

        #endregion

        #region Public Field

        public enum CodeType { Words, Numbers, Characters, Alphas }

        #endregion

        #region Private Methods



        private string GenerateNumbers ()
        {

            string strOut = "";

            System.Random random = new Random();

            for (int i = 0 ; i < _len ; i++)
            {

                string num = Convert.ToString(random.Next(10000) % 10);

                strOut += num;

            }

            return strOut.Trim();

        }



        private string GenerateCharacters ()
        {

            string strOut = "";

            System.Random random = new Random();

            for (int i = 0 ; i < _len ; i++)
            {

                string num = Convert.ToString((char)(65 + random.Next(10000) % 26));

                strOut += num;

            }

            return strOut.Trim();

        }

        // 

        private string GenerateAlphas ()
        {

            string strOut = "";

            string num = "";

            System.Random random = new Random();

            for (int i = 0 ; i < _len ; i++)
            {

                if (random.Next(500) % 2 == 0)
                {

                    num = Convert.ToString(random.Next(10000) % 10);

                }

                else
                {

                    num = Convert.ToString((char)(65 + random.Next(10000) % 26));

                }

                strOut += num;

            }

            return strOut.Trim();

        }



        private System.Drawing.Bitmap TwistImage ( Bitmap srcBmp, bool bXDir, double dMultValue, double dPhase )
        {

            System.Drawing.Bitmap destBmp = new Bitmap(srcBmp.Width, srcBmp.Height);



            // 将位图背景填充为白色 

            System.Drawing.Graphics graph = System.Drawing.Graphics.FromImage(destBmp);

            graph.FillRectangle(new SolidBrush(System.Drawing.Color.White), 0, 0, destBmp.Width, destBmp.Height);

            graph.Dispose();



            double dBaseAxisLen = bXDir ? (double)destBmp.Height : (double)destBmp.Width;



            for (int i = 0 ; i < destBmp.Width ; i++)
            {

                for (int j = 0 ; j < destBmp.Height ; j++)
                {

                    double dx = 0;

                    dx = bXDir ? (PI2 * (double)j) / dBaseAxisLen : (PI2 * (double)i) / dBaseAxisLen;

                    dx += dPhase;

                    double dy = Math.Sin(dx);



                    // 取得当前点的颜色 

                    int nOldX = 0, nOldY = 0;

                    nOldX = bXDir ? i + (int)(dy * dMultValue) : i;

                    nOldY = bXDir ? j : j + (int)(dy * dMultValue);



                    System.Drawing.Color color = srcBmp.GetPixel(i, j);

                    if (nOldX >= 0 && nOldX < destBmp.Width

                     && nOldY >= 0 && nOldY < destBmp.Height)
                    {

                        destBmp.SetPixel(nOldX, nOldY, color);

                    }

                }

            }



            return destBmp;

        }

        #endregion

        #region Public Methods

        public Stream CreateCheckCodeImage ()
        {
            string checkCode;
            switch (_codetype)
            {
                case CodeType.Alphas:
                    checkCode = GenerateAlphas();
                    break;
                case CodeType.Numbers:
                    checkCode = GenerateNumbers();
                    break;
                case CodeType.Characters:
                    checkCode = GenerateCharacters();
                    break;
                default:
                    checkCode = GenerateAlphas();
                    break;
            }
            this._checkCode = checkCode;

            if (checkCode == null || checkCode.Trim() == String.Empty)
                return null;

            // 计算图片宽度，确保有足够空间显示所有字符
            int imageWidth = (int)Math.Ceiling((checkCode.Length * _jianju));
            Bitmap image = new System.Drawing.Bitmap(imageWidth, (int)_height);
            Graphics g = Graphics.FromImage(image);

            try
            {
                Random random = new Random();
                g.Clear(Color.White);

                // 使用更大的字体
                Font font = new System.Drawing.Font("Arial", 16, System.Drawing.FontStyle.Bold);

                // 使用纯色而不是渐变色
                SolidBrush brush = new SolidBrush(Color.FromArgb(51, 51, 51));

                // 计算垂直居中位置
                float y = (_height - font.Height) / 2;

                // 绘制验证码
                for (int i = 0 ; i < checkCode.Length ; i++)
                {
                    g.DrawString(checkCode.Substring(i, 1), font, brush, 3 + i * _jianju, y);
                }

                // 添加简单的干扰线
                for (int i = 0 ; i < 3 ; i++)
                {
                    int x1 = random.Next(image.Width);
                    int x2 = random.Next(image.Width);
                    int y1 = random.Next(image.Height);
                    int y2 = random.Next(image.Height);
                    g.DrawLine(new Pen(Color.FromArgb(200, 200, 200), 1), x1, y1, x2, y2);
                }

                // 轻微扭曲
                image = TwistImage(image, true, 0.8, 0.2);

                // 画边框
                g.DrawRectangle(new Pen(Color.FromArgb(200, 200, 200)), 0, 0, image.Width - 1, image.Height - 1);

                MemoryStream ms = new System.IO.MemoryStream();
                image.Save(ms, System.Drawing.Imaging.ImageFormat.Png);  // 使用PNG格式以获得更好的质量
                return ms;
            }
            finally
            {
                g.Dispose();
                image.Dispose();
            }
        }

        #endregion
    }
}
